This project is concerned with the evaluation of a variety of new and existing diagnostic techniques which have yet to be applied to biomedical diagnostic applications having particular relevance to dentistry. It is largely a continuation of work done in previous years which dealt with the development of quantitative methods for measuring factors believed to be associated with relatively long-term changes of diagnostic interest in dental tissues. Modalities studied include quantitative radiology, nuclear medicine (99mTc-MDP), and fiber-optic systems making use of visible light (hemoglobin-specific spectrum analysis). New algorithms are being used to extend the application of digital subtraction radiography to include longitudinal assay of experimentally simulated, progressive, bone lesions in phalanges and femur. Preliminary data have shown that spectrometrically confirmed, diffuse, changes of as little as 0.3% are readily discernible. Rationmetric assessment of scattered light continues to be used to evaluate tooth vitality. In vitro data obtained using a prototype, filtered, fiber-optic system designed to detect the presence of oxygenated blood in the pulp chamber show that tiny changes in tooth color measured in this way can be used to predict degenerative changes seen invariably in recently extracted teeth after storage for a week or more in saline at 37 degrees C. Measurements of differential uptake of 99mTc-MDP in two beagle dogs following periodontal surgery are being replicated to confirm earlier findings which suggested that the dynamics of wound healing in periodontal bone can be predicted from baseline measurements in these animals.